In order to address concentration of accesses by clients in a client-server system, a cluster method is proposed in which a plurality of servers mutually collaborates to share the load. Compared with personal authentication systems that use a password and/or a Personal Identification Number (PIN), biometric authentication systems that perform biometric authentications generally have a large authentication processing load. Accordingly, the biometric authentication system may share the load by the cluster method according to the size (number) of clients.
Although clustering of servers achieves a certain effect to share the load, expected performance may not be achieved depending on how much authentication requests are concentrated on at specific time. Accordingly, a technique is proposed in which authentication data is registered in a cache memory of a client and so on and verification is performed by using the authentication data registered in the cache memory, and thereby reducing, if not preventing, to cause an excessive load to servers or the network. Moreover, the following technique is proposed. According to the technique, a certain pieces of authentication data is stored in a database (DB) of a device that is different from a server that retain all of the authentication data, verification is performed using the certain piece of authentication data. As a result, authentication requests that are assumed to be failed on the server are reduced and an excessive load to the server may be reduced, if not prevented (for example, Japanese Laid-open Patent Publication No. 2003-44442, Japanese Laid-open Patent Publication No. 2001-256191 and Japanese Laid-open Patent Publication No. 2005-142848).